The demand for ever higher circuit board density has resulted in small size semiconductors devices having a low profile. With the improvements on the packaging technology, methodology such as surface mounting technology (SMT) becomes popular for manufacturing a miniaturized semiconductor package. In the SMT, a carrier mounts and electrically connects with another carrier by various manner. For example, the carrier is mounted on a surface of another carrier through a number of solder balls. The solder balls dispose respectively on a number of pads of the carrier, then the solder balls dispose on corresponding pads on the surface of another carrier. The solder balls bond the pads of the carrier and the pads of another carrier by a heat treatment to form solder bumps, so that the carrier electrically connects and integrates with another carrier.
By bonding the carrier on another carrier through disposition of the solder bumps between the pads of the carrier and the pads of another carrier, an electrical resistance and a required space for occupying components and circuits are both reduced. However, a reliability of the solder bumps affects a manufacturing yield of the semiconductor package. A failure on a single solder bump causes a fatal malfunction of the semiconductor package. Different attempts have been made to improve a structure of the semiconductor package and a method for manufacturing the semiconductor package. Such improvements however each have their own deficiencies.